I have very limited experience, but one of the most impressive sounds that I have heard was using a Pathos Logos integrated that retails for about $5,000. Personally, I'd at least rule out a Pathos product before purchasing something else. I know they have at least one other integrated.

Krell impressed with everytime I've heard a system with it's amplifiers or even the S-300i integrated, but they are all solid state so it isn't what you're looking for.